1. Field of the Invention
The invention relates to transportation engineering, and, in particular, it deals with a magnetic suspension for a vehicle designed for passenger and freight transportation.
2. Description of the Prior Art
Known in the art are magnetic suspensions wherein an underframe of a vehicle moves along a guide rail horizontally extending on a track, and an air gap is provided between cooperating members of the magnetic suspension, e.g. between magnetic poles of the underframe and guide rail, owing to the mutual repulsion of magnets of the underframe and guide rail, respectively.
However, during the movement, the air gap changes during vertical oscillations of the vehicle underframe under the action of various perturbances thus endangering the movement. For this reason, the air gap between the cooperating members of the magnetic suspension should be increased resulting in an increased energy consumption and weight of the magnets. In addition, the surfaces of magnetic strips of the suspension which are installed on the track are prone to fouling with foreign objects and atmospheric precipitates so that there is an added cost of track cleaning and inspection. These are the main factors hampering wide application of magnetic suspensions for vehicles with horizontally extending guide rails.
Magnetic suspensions with vertically extending cooperating members appear to be more promising. With such an arrangement, all of the vertical oscillations of the underframe with respect to the track would not result in a change in the gap between the cooperating members of the magnetic suspension, the gap remaining substantially constant. Such magnetic suspensions are not prone to fouling with foreign objects and atmospheric precipitates as they cannot hold on the guide rail.
The air gap which does not depend on oscillations of the underframe and the immunity of such magnetic suspensions to fouling enables one to reduce the gap between the surfaces of the cooperating members as compared to the above structures so that the load carrying capacity of a vehicle can be increased.
Among such magnetic suspensions is a magnetic suspension disclosed in U.S. Pat. No. 3,828,686. The magnetic suspension comprises guide rails made of a ferromagnetic material and installed on the track, and an electrical winding mounted on the underframe of a vehicle and on a core vertically extending between guide rails.
This magnetic suspension does not, however, have reliability which would be adequate for transportation purposes, since an interruption of power supply of the electrical winding results in the loss of lifting force of the suspension and in accidents. In addition, the magnetic suspension of this type requires a high accuracy of the relative position of the guide rails and core since a sufficient stability (gradient) of lifting force cannot be achieved within the actually occurring range of vertical displacements of the vehicle underframe.
The closest prior art of the invention is a magnetic suspension of a vehicle (cf. USSR Inventor's Certificate No. 464469, Cl. B21B, 1982), comprising a guide rail vertically installed on the track and having lateral sides of a magnetically conducting material, and an underframe surrounding the lateral sides of the guide rail and having a magnetic system in the form of horizontally extending strips of magnets, the polarity of the pole facets of the magnets facing toward the lateral sides of the guide rail alternating in the vertical direction. The magnetic system also comprises a means for lateral stabilization of the underframe preventing it from asymmetrically displacing with respect to the guide rail. The magnets of the underframe create magnetic fluxes that close at teeth provided on the lateral side of the guide rail. During a vertical displacement of the vehicle underframe, the lifting force of the suspension passing through its maximum will decrease to zero when the teeth of the guide rail will be disposed symmetrically with respect to two adjacent pole facets of the electromagnet, i.e. the zone of admissible vertical displacements of the vehicle underframe should be smaller than one half the distance between adjacent pole facets of the magnets of the vehicle underframe so that the amount of admissible vertical displacements of the underframe is limited and high accuracy is required in the manufacture of the guide rail so as to ensure the desired stability of a vehicle. In addition, in the magnetic suspension of this type, it is necessary to ensure a high magnitude of magnetizing force of the magnets since magnetic flux created by the magnets of the underframe is closed through two air gaps. These circumstances discourage the use of permanent magnets in the magnetic suspension as sources of magnetic field, since a magnetizing force of permanent magnets in such a suspension remains inadequate for building-up the necessary lifting force. Such magnetic suspension can only be built with electromagnets that feature high energy consumption and require many non-ferrous metals for their manufacture while, at the same time, lacking reliability because an interruption of power supply results in disappearance of lifting force and in emergency situations.